Printing ink



Patented Apr. 3, 1923.

UNITED STATES PATENT OFFICE.

WILLIAM J. MCELROY, OF NEW YORK, AND JOHN CLARKE, OF MANI-IASSET,

NORTH HEMPSTEAD, NEW YORK, ASSIGNORS, BY MESNE ASSIGNMENTS, T0 AL- CHEMIC GOLD COMPANY, INC., A CORPORATION OF NEW YORK.

PRINTING INK.

No Drawing.

To all whom it may concern:

Be it known that we, WILLIAM J. MCEL nor, a citizen of the United States, and a resident of the borough of Manhattan, city, county, and State of New York, and JOHN CLARKE, a citizen of the United States, and a resident of the village of Manhasset, town of North Hempstead, county-of Nassau, and State of New York, have invented a new and useful Improvement in Printing Inks, of which the following is a description, as well as of the manner and process of making, constructing. compounding, and using the same, in such full, clear, concise, and exact terms as to enable any person skilled in the art or science to which it appertains or with which it is most nearly connected to make, construct, compound, and use the same.

Our invention relates generally to printing inks and particularly to those having metallic powders as their pigments.

The objects of our invention are the-production of improved printing inks adapted for general use and more especially for use in embossing and die-printing upon bookcloth, leather and other materials commonly used for book casings; particular objects are the production of inks of this class which shall be adapted for application by a heated die, plate or other impression member, preheated to embossing temperatures, and which shall be characterized by the qualities of drying immediately under the relatively high temperature preferred in embossing metallic powders; and having properties of strongly adhering to and covering smoothly, evenly and completely the surface upon which they are stamped; of being rendered lustrous by the heat of the metal by which they are impressed upon such object; of permanently retaining their original color and luster without tarnishing or fading;

of high boiling point and of low volatility.

' Further objects are the provision of an ink with the foregoing qualities which can be mixed ready for use by the manufacturer and which will not corrode or otherwise deteriorate in the container, and which, when packaged, and transported shall remain'in its original state with its qualities ,and both its physical and chemical conditions unimpaired even after long lapse of time.

We have heretofore disclosed in our co- Application filed June 16, 1922. Serial No. 568,849.

an adhesive to the articles stamped, and as a protective coating to the impressed me t-allic deposit when printed.

The coumarone resins are coal tar condensation products derived from coumarone and indene which are themselves constituents of coal tar naphtha. They are usually yellow in color, and particularly well suited to conjunction with those bronze powders customarily employed as pigments in socalled imitation gold leaf, gold ink and the like compositions. blending therewith without detracting from their pigmentation. While the particular example selected by way of illustration is a gold ink, it is obvious that there are varying shades of bronze powders in the imitation gold powders. and a. wide range of metallic pigments known as bronze powders imitating other metals. such as silver and aluminum. These synthetic resins dissolve readily in such energetic solvents as terpineol, pine oil, rosin oil, and the high-boiling mineral oils. Because of its body, which is well adapted to maintain bronze powders in suspension, and its volatility at embossing temperatures, we prefer terpineol as a solvent vehicle for this coumarone binder. As the binder becomes volatile at these temperatures, we prefer ably admix with the terpineol a small per cent of rosin oil. Since rosin oil at such temperatures is less volatile than terpineol, the'mixture preferred as a solvent is approximately 95 per cent of terpineol and five per cent of rosin oil, such minor percentage suflicing to render the binder more plastic when dried, whereby the ink impression is prevented from'cracking or scaling off. Rosin oil, because of its low vol-- atility, is not suitable alone as such solvent,

because of the slow drying of the ink impression. Pine oil as a solvent is subject to the like disadvantage imported by terpineol, leaving the impression too brittle. It is not as valuable for the desired purposes because it is commercially variable as a manufactured product, its definite chemical composition not being standardized. If neutral in character, it is suit-able as a solvent, but as now produced, it is liable to be acid or to become so when exposed to the air, and react upon the metallic pigments undesirably; otherwise it affords, when mixed with the proper proportions of rosin oil, a suitable non-acid vehicle for the binder.

As an example of the preferred proportions of the ingredients named, we take, by weight, 95 per cent terpineol and 5 per cent rosin oil, and stir until thoroughly mixed.

\Vith 84 per cent of this mixture we incorporate 16 per cent of powdered coumarone resin, e. g., that known under the trade name of Cumar, and warm this mixture upon a water-bath at 100 centigrade, stirring meanwhile, until the Cumar is thoroughly dissolved, which will result in about 20 minutes with vigorous stirring. The batch is then allowed to cool. From this batch we take one-third and add thereto two-thirds of bronze powder, both by weight. This mixture is then stirred until the bronze powder is thoroughly and evenly incorporated. The ink resulting is of pasty and semi-fluid consistency, similar to that of printing inks generally.

As the metallic pigment above intended, we prefer a mixture of bronze powder of the grade known commercially as Hemmerdingers Special No. 1, with 80 per cent of which is mixed 20 per cent of the finer grade of bronze powders known generally in the trade as Lining, a more finely comminuted species of such powders.

The proportions above exampled may be varied somewhat without appreciable variation of the product. However, 20 per cent of Cumar to 80 er cent of solvent vehicle forms an ink wiiich at certain temperatures tends to clog the impression member. 10.. per cent of rosin oil tends under certain temperatures to give a too wet impression, which, until dried, is liable to be too tacky and to smudge. 100 per cent terpineol tends to produce a too brittle impression. The ratio of bronze to vehicle affords more latitude of variation, but an excess of bronze does not work well on the press and clogs the die, the practical limit being about 23; parts of bronze to one of vehicle.

While thus specifying terpineol and rosin oil as the constituents preferred of our binder solvent vehicle, we wish to be understood as typifying thereby a binder vehicle having the desired properties as such, first, of an active solvent of the synthetic resins named; second, as of the desired body adapt ed to maintain the bronze powders in sustained suspension; third, as of the requisite degree of volatility to be driven off by the temperature used in embossing metallic pigments to impart the desired luster thereto; fourth, affording that degree of plasticity and elasticity to the impression which will prevent its cracking; fifth, the necessary neutrality which will preserve the metallic particles from corrosion on standing when mixed in ink form; sixth, which shall not cause the impressed characters to tarnish; and seventh, which shall be colorless or of such color as will not detract from the desired metallic luster. Vithin the limitations imposed by these criteria, the binder vehicle may be any of the solvents named or suitable combinations thereof. This printing composition is primarily intended for printing book covers which, when of cloth, are prepared as cases with a strong coating of glue to hold the cloth to the backing. As the boiling point of the vehicle specified is approximately 428 Fahrenheit, the impression temperature must suflice to drive off the volatile solvent, that the impression may be dry, but must not be so high as to draw the glue through the cloth and thereby cause blisters in the impression or darken it. Preferably, therefore, the described composition should be used as an ink at a temperature substantially that of the boiling point of the solvent vehicle. As will be obvious, however, the ink set forth may be used at lower temperatures, or cold. and the impression artificially dried thereafter.

By virtue of the comparatively high specific gravity of the synthetic resins produced as condensation products of naphtha, and the heavy body of the solvents therefor herein named, the solution obtained affords an especially valuable vehicle for the metallic pigments in that the tendency of the bronze powder to settle is checked and a persistent suspension thereof is attained.

Having thus described the preferred embodiment of our invention and the best method now known to us of producing and usefully applying same, we 'claim 1. A printing composition comprising a metallic pigment. a binder therefor consisting of a neutral synthetic resin, and a neutral solvent therefor, the said soh'ent being volatile at temperatures between 400 and 500 Fahrenheit, and the ,binder being adapted to constitute a protective coating to the impressed pigment.

2. A printing composition comprising a metallic pigment, a binder therefor consisting of a neutral synthetic resin, a. volatile neutral solvent therefor. and an oil less volatile than the solvent adapted to blend with the binder and render it flexible when impressed.

3. A printing composition comprising a metallic pigment, a'binder and a high-boiL' ing neutral solvent, the binder consisting of a. co-umarone resin,

4. A printing composition comprising a metallicpigment, a coumarone resin, and terpineol. I

5. A printing composition comprising a metallic pigment, a coumarone resin, terpineol, and rosin oil.

6. A printing composition comprising ametallic pigment, a coumarone resin, and a high-boiling heavy-bodied neutral oil adapted to dissolve said resin.

7. A printing composition comprising a metallic pigment, a synthetic resin, and a high-boiling heavy-bodied neutral solvent of an oily character.

8. A printing composition comprising a metallic pigment, a synthetic resin, and a heavy-bodied neutral solvent.

9'. A printing composition comprising a metallic pigment, a synthetic'resin and terpineol. I

10. A printing composition comprising, a metallic pigment, a synthetic resin, terpineol, and rosin oil.

11. A printing composition composed of the recited ingredients in the following proportions by Weight: 16 per cent of coumarone resin dissolved in 84 per cent of a solvent composed of 95 per cent terpineol and 5 per cent rosin oil; With metallic powder pigment in the proportion of two parts of pigment to one part of the resin solution.

12. A printing composition comprising.

the recited ingredients in the following proportions, by weight: 16 per cent of a nonacid synthetic resin dissolved in 84 per cent of a non-acid solvent and metallic pigment in the proportion of two parts of pigment to one part of the solution.

' WILLIAM J. MoELROY.

JOHN CLARKE. 

